Kelce was placed on injured reserve Tuesday after he had surgery to repair a torn medial collateral ligament in his right knee. Once that heals in about a month, he will have surgery to repair a torn anterior cruciate ligament. That'll require six to 12 months recovery time.

"We never really compare these guys to any other player because they all play different positions, they have different body types, and they have different angles in their knees," Eagles head athletic trainer Rick Burkholder said. "They have different strengths and weaknesses. But, with everything we know about Kelce, we think that he is going to make a recovery. We think it's going to be an MCL repair, which takes six weeks to heal up, and then an ACL which takes nine months.

"We'll go from there."

The Eagles, off to a 2-0 start for the first time since 2004, were hoping Kelce wouldn't need the ACL operation. On Monday, Burkholder said there was a chance he might return within six weeks. But it was determined during Tuesday's procedure that Kelce will need complete knee reconstruction.

"I think he knew he had a knee injury that was pretty significant just from what he felt on the field and what he saw on tape," Burkholder said. "I think he was hoping for the best, but prepared himself for the worst."

Center Steve Vallos was signed to take Kelce's roster spot. Dallas Reynolds will be the starter. Reynolds filled in nicely after Kelce went down in Sunday's win over the Baltimore Ravens. Reynolds, 28, had spent three seasons on the practice squad before taking his first snap in the NFL.

Vallos spent training camp with the Eagles before he was released as part of the team's final roster cut down. Vallos has started eight games in four seasons with the Seattle Seahawks and Cleveland Browns.

A sixth-round pick last year, Kelce started every game his rookie season and played all but six snaps. He's the second starter to be lost for an extended period. All-Pro left tackle Jason Peters tore his right Achilles tendon in the offseason and is on the non-football injury list. He's eligible to return to practice with the team between Weeks 6-9 of the regular season, though it's uncertain if he can.